In general, protein kinases are the largest set of structurally related phosphoryl transferases, have highly conserved structures and catalytic functions and may be categorized into families by the substrates they phosphorylate (e.g., protein-tyrosine, protein-serine/threonine, histidine and the like) and are responsible for the control of a wide variety of cellular signal transduction processes.
Examples of protein-tyrosine kinases include, but are not limited to, Irk, IGFR-1, Zap-70, Bmx, Btk, CHK (Csk homologous kinase), CSK (C-terminal Src Kinase), Itk-1, Src (c-Src, Lyn, Fyn, Lck, Syk, Hck, Yes, Blk, Fgr and Frk), Tec, Txk/Rlk, Abl, EGFR (EGFR-1/ErbB-1, ErbB-2/NEU/HER-2, ErbB-3 and ErbB-4), FAK, FGF1R (also FGFR1 or FGR-1), FGF2R (also FGR-2), MET (also Met-1 or c-MET), PDGFR (α and β), Tie-1, Tie-2 (also Tek-1 or Tek), VEGFR1 (also FLT-1), VEGFR2 (also KDR), FLT-3, FLT-4, c-KIT, JAK1, JAK2, JAK3, TYK2, LOK, RET, TRKA, PYK2, ALK (Anaplastic Lymphoma Kinase), EPHA (1-8), EPHB (1-6), RON, Fes, Fer or EPHB4 (also EPHB4-1).
Examples of protein-serine/threonine kinases include, but are not limited to, Ark, ATM (1-3), CamK (I-IV), CamKK, Chk1 and 2 (Checkpoint kinases), CKI, CK2, Erk, IKK-I (also IKK-ALPHA or CHUK), IKK-2 (also IKK-BETA), Ilk, Jnk (1-3), LimK (1 and 2), MLK3Raf (A, B, and C), CDK (1-10), PKC (including all PKC subtypes), Plk (1-3), NIK, Pak (1-3), PDK1, PKR, RhoK, RIP, RIP-2, GSK3 (α and β), PKA, P38, Erk (1-3),PKB (including all PKB subtypes) (also AKT-1, AKT-2, AKT-3 or AKT3-1), IRAK1, FRK, SGK, TAK1 or Tpl-2 (also COT).
Protein kinases play very important roles in the normal regulation of cell growth. However, as a result of dysregulation of the tyrosine kinases (receptor or non-receptor) or the ligands of the receptor tyrosine kinases, signaling can become deregulated, resulting in uncontrolled cell proliferation leading to cancer or a related disease, disorder or syndrome.
Protein kinases catalyze and regulate the process of phosphorylation, whereby the kinases covalently attach phosphate groups to proteins or lipid targets in response to a variety of extracellular signals: hormones, neurotransmitters, growth and differentiation factors, cell cycle events, environmental stresses, nutritional stresses and the like.
Phosphorylation modulates or regulates a variety of cellular processes such as proliferation, growth, differentiation, metabolism, apoptosis, motility, transcription, translation and other signaling processes. Defective control of protein phosphorylation due to unregulated cellular mitosis, unregulated cell proliferation and upregulated kinase activity has been implicated in a number of diseases and disease conditions, such as osteoarthritis, rheumatoid arthritis, synovial pannus invasion in arthritis, multiple sclerosis, myasthenia gravis, diabetes mellitus, diabetic angiopathy, diabetic retinopathy, retinal vessel proliferation, inflammatory bowel disease, Crohns disease, ulcerative colitis, bone diseases, transplant or bone marrow transplant rejection, lupus, chronic pancreatitis, cachexia, septic shock, fibroproliferative and differentiative skin diseases or disorders, central nervous system diseases, neurodegenerative diseases, disorders or conditions related to nerve damage and axon degeneration subsequent to a brain or spinal cord injury, acute or chronic cancer, occular diseases, viral infections, heart disease, lung or pulmonary diseases or kidney or renal diseases. Therefore, kinase inhibitors have potential use as therapeutic agents.
The term “myasthenia gravis” means a disease having the characteristic feature of easy fatigue of certain voluntary muscle groups on repeated use. Muscles of the face or upper trunk are especially likely to be affected. In most and perhaps all cases, the disease is due to the development of autoantibodies against the acetylcholine receptor in neuromuscular junctions. Immunization of animals with this receptor protein leads to a disease with the features of myasthenia gravis.
In reference to “synovial pannus invasion in arthritis,” the term “pannus” means a disease whereby vascularised granulation tissue rich in fibroblasts, lymphocytes and macrophages, derived from synovial tissue, overgrows the bearing surface of the joint in rheumatoid arthritis and is associated with the breakdown of the articular surface.
The tyrosine kinases can further be categorized by whether they are receptor tyrosine kinases or non-receptor tyrosine kinases. The receptor tyrosine kinases span the cell membrane with a ligand interacting domain protruding from the cell, with a hydrophobic trans-membrane domain, and a cytoplasmic domain that contains the catalytic kinase domain and other regulatory sequences. Non-receptor tyrosine kinases are often myristylated or modified by the addition of other hydrophobic moieties that allow them to be anchored to the cell membrane.
The epidermal growth factor receptor (EGFR) tyrosine-kinase family includes the receptors EGFR (also referred to as EGFR-1 or Erb-B1), HER-2 (or neu), EGFR3 and EGFR4. Epidermal Growth Factor (EGF), Transforming Growth Factor-α (TGF-α) and the HER-2 ligand heregulin are three of the ligands that bind to the EGFR receptors.
EGFR overexpression or mutation of one or more EGFR kinase family members has been commonly involved in cancer and other diseases characterized by uncontrolled or abnormal cell growth. Deregulation of EGFR has also been associated with epidermoid tumors, head and neck tumors, breast tumors and tumors involving other major organs, such as the lungs and gastointestinal tract. The clinically prevalent cancers related to EGFR include lung, gastric and head and neck cancer (Klijn J G, Berns P M, Schmitz P I and Foekens J A; The clinical significance of epidermal growth factor receptor (EGF-R) in human breast cancer: a review on 5232 patients, Endocr. Rev., 1992, 13, 3-17; Salomon D and Gullick W; The erbB family of receptors and their ligands: Multiple targets for therapy, Signal, 2001, 2, 4-11). Other diseases associated with increased EGFR expression include proliferative glomerulonephritis, diabetes-induced renal disease and chronic pancreatitis.
In treating cancers of the head such as brain cancers and the like, the ability of small molecule EGFR inhibitors to penetrate the blood brain barrier could have therapeutic advantages since EGFR is often overexpressed in primary brain tumors and also in breast and non-small cell lung carcinomas that frequently metastasize to the brain (Eckstrand A J, Sugawa N, James C D and Collins V P; Amplified and rearranged epidermal growth factor receptor genes in human glioblastomas reveal deletions of sequences encoding portions of the N-and/or C-terminal tails, Proc. Acad. Natl. Sci. USA, 1992, 89, 4309-4313; and, Wickstrand C J, Hale L P, Batra S K, Hill M L, Humphrey P A, Kurpad S N, McLendon R E, Moscatello D, Pegram C N, Reist C J, Traweek S T, Wong A J, Zalutsky M R and Bigner, D D; Monoclonal antibodies against EGFRvIII are tumor specific and react with breast and lung carcinomas and malignant gliomas, Cancer Res., 1995, 55, 3140-3148).
EGFR inhibitors tested in neurite outgrowth assays have activity in promoting neurite outgrowth in both cerebellar granule cells and dorsal root ganglion neurons, likely by acting directly on neurons to block neuronal inhibitory responses to myelin inhibitors, and thus an EGFR inhibitor may have potential use for promoting axon regeneration after brain and spinal cord injury (V. Koprivica, et al, EGFR activation mediates inhibition of axon regeneration by myelin and chondroitin sulfate proteoglycans, Science, 2005, 310, 106).
HER1 and HER2 overexpression has been implicated in a variety of cancers, such as bladder, breast, colorectal, endometrial, esophageal, gastric (stomach), glioma head and neck, lung (non-small cell lung cancer), ovarian, pancreatic, renal and prostate cancer.
Comparing the overexpression of HER1 and HER2 in tumors, according to order of prevalence, HER1 overexpression is found in breast, renal cell, lung, colorectal, head and neck, ovarian, pancreatic, glioma, bladder, esophageal, gastric, endometrial and cervical cancer tumors; in contrast, HER2 overexpression is found in esophageal, head and neck, lung, gastric, renal cell, breast, bladder, ovarian and colorectal, prostate and endometrial cancer tumors (Horizons in Cancer Therapeutics: From Bench to Bedside, Signal Transduction Inhibitors, 2001, 2(2), ISSN 1532-3048).
While the degree of HER2 overexpression in breast and ovarian cancer is not as great as in some other cancers, HER2 has been found to be responsible for these clinically prevalent cancers (Slamon D J, Clark G M, Wong S G, Levin W J, Ullrich A and McGuire W L; Human breast cancer: Correlation of relapse and survival with amplification of HER-2/neu oncogene, Science, 1987, 235, 177-82; Slamon D J, Godolphin W, Jones L A, Holt J A, Wong S G, Keith D E, et al; Studies of the HER-2/neu proto-oncogene in human breast and ovarian cancer, Science, 1989, 244, 707-712; Hetzel D J, Wilson T O, Keeney G L, Roche P C, Cha S S and Podrantz K C; HER-2/neu expression: A major prognostic factor in endometrial cancer, Gynecol. Oncol., 1992, 47, 179-85).
Furthermore, patients with HER-2 overexpressing breast cancer frequently experience metastases to the brain (Kirsch D G and Hochberg F H; Targeting HER-2 in brain metastases from breast cancer, Clin. Can. Res., 2003, 9, 5435-5436). These patients have an extremely poor prognosis and intracerebral tumors are often the cause of death. Autopsy revealed that 20-30% of patients who die of breast cancer have brain metastases (Grossi P M, Ochiai H, Archer G E, McLendon R E, Zalutsky M R, Friedman A H, Friedman H S, Bigner D D and Sampson J H; Efficacy of intracerebral microinfusion of trastuzumab in an athymic rat model of intracerebral metastatic breast cancer, Clin. Can. Res., 2003, 9, 5514-5520).
Human cytomegalovirus (CMV) is a widespread opportunistic human herpes virus that causes severe and fatal diseases in those who are immune compromised and in transplant recipients. CMV is also a leading cause of atherosclerosis and virally mediated birth defects. The human CMV uses the EGFR receptor to enter cells during infection, EGFR is autophosphorylated and the downstream signal transduction pathway components are activated; however, the EGFR specific inhibitor tyrphostin AG1478 has been shown to reduce the viral load in cells that were infected in the presence of the tyrphostin (Wang X, et al., Nature, 24 Jul. 2003, Vol 424, 456-461). Accordingly, potent EGFR selective inhibitors may be useful in anti-CMV therapy.
The Src family of tyrosine-kinases includes the sub-family proteins c-Src, Lyn, Fyn, Lck, Syk, Hck, Yes, Blk, Fgr and Frk. While various members of the c-Src family are important for normal cellular proliferation, their overexpression and overactivation can promote development of cancer (Yeatman T J, Nature, June 2004, Vol. 4). For example, the Lyn kinase has been shown to be upregulated in hormone resistant prostate cancer. Tumor xenografts of hormone resistant prostate cancer cells showed delayed growth upon treatment with peptides that specifically block Lyn kinase activity (Goldenberg-Furmanov, et al., Cancer Research, 1 Feb. 2004, 64, 1058-1064).
The Lyn and Hck Src sub-family tyrosine-kinases have both been implicated in chronic myeloid leukemia (CML). CML is caused by the BCR-Abl fusion protein resulting from the t(9;22) chromosomal translocation that juxtaposes the c-Abl non-receptor tyrosine kinase gene on chromosome 9 with a breakpoint cluster region (bcr) gene on chromosome 22. The BCR-Abl fusion protein is a constitutively activated form of the Abl tyrosine kinase that drives uncontrolled growth leading to CML and many cases of adult acute lymphoblastic leukemia. Gleevec is an inhibitor of Abl that has been successfully used to treat CML. However, Gleevec does not help patients in blast crisis because they carry mutant forms of BCR-Abl that no longer bind Gleevec. Such Gleevec resistant CML cells are sensitive to a dual src/BCR-Abl inhibitor that binds and inhibits the mutant BCR-Abl and members of the src family (Shah, et al., Science, 16 Jul. 2004, Vol 305, 399-401). CML cells can also become resistant to treatment with the tyrosine kinase Abl inhibitor Gleevec in other ways. For example, CML K562 cells that become resistant to Gleevec minimize reliance on the BCR-Abl translocation for growth and instead upregulate the Lyn and Hck kinases, as demonstrated by expressing antisense Lyn in these cells, which reduced their rate of proliferation (Donato, et al., Blood, 15 Jan. 2003, 101(2)). c-Src and other Src family members are also involved in cellular adhesion, invasion and motility of tumor cells. Thus, small molecule inhibitors of the Src kinase family could offer new therapeutic opportunities for both leukemias and solid tumors.
Aurora kinases (Aurora-A, Aurora-B and Aurora-C) are highly conserved tyrosine kinases found in all organisms where they function to regulate microtubule dynamics during the M phase of the cell cycle and are essential for mitotic progression. Aurora-A kinase associates with the centrosome around the pericentriolar material, as well as the microtubules at the bipolar mitotic-spindle poles and the midbody microtubules and plays a role in spindle formation and organization of the centrosome. Aurora-B regulates chromosomal movement and cytokinesis and Aurora-C's biological function is not yet understood. The Aurora-A kinase is involved in centrosome separation, duplication and maturation as well as in bipolar spindle assembly and stability. Aurora-A is overexpressed in a number of different human cancers and tumor cell lines. Overexpression of Aurora is sufficient to induce growth in soft agar and transforms cells making them tumorigenic. Inhibition of Aurora activity results in centrosome/chromosome segregation defects leading to monopolar spindles and polyploidy which induces cell apoptosis in a variety of cancer cell lines and has suppressed tumor growth in vivo.
Angiogenesis plays a role in various processes including development of the vasculature, wound healing and maintenance of the female reproductive system. Pathological angiogenesis is associated with disease states such as cancer, diabetic retinopathy, rheumatoid arthritis, endometriosis and psoriasis. Solid-tumor cancers, in particular, are dependent on angiogenesis for their growth. The vascular endothelial growth factors (VEGFs) are mediators of both normal and pathologic angiogenesis. VEGF transmits signals into cells through their cognate receptors, which belong to the receptor tyrosine kinase (RTK) family of transmembrane receptors. These receptors are tripartite, consisting of an extracellular ligand-binding domain, a transmembrane domain, which anchors the receptor in the membrane of the cell, and an intracellular tyrosine kinase domain.
One subfamily of RTKs comprises the receptors Flt1/VEGF-R1 and KDR/Flk1/VEGF-R2, which bind VEGFs. Binding of the VEGF ligand to the receptor results in stimulation of the receptor tyrosine kinase activity and transduction of biological signals into the cell. The KDR/Flk1/VEGF-R2 receptor mediates the biological activities of mitogenesis and proliferation of endothelial cells while the Flt1/VEGF-R1 receptor mediates functions such as endothelial cell adhesion. Inhibition of KDR/Flk1/VEGF-R2 signalling has been shown to inhibit the process of angiogenesis. Inhibitors of this receptor are likely useful in controlling or limiting angiogenesis.
There is a need for potent small-molecule kinase inhibitors of one or more of the EGFR, HER-2, c-Src, Lyn, c-Abl, Aurora-A or VEGF kinase proteins and the like possessing anti-tumor cell proliferation activity, and as such are useful in treating or ameliorating a EGFR, HER-2, c-Src, Lyn, c-Abl, Aurora-A or VEGF kinase receptor mediated, angiogenesis-mediated or hyperproliferative disorder.